/Engine/Source/Runtime/SlateCore/Public/Rendering/SlateDrawBuffer.h
Creates a newFSlateWindowElementListand returns a reference to it so it can have draw elements added to it
[FSlateWindowElementList](API\Runtime\SlateCore\Rendering\FSlateWindowElementList) & AddWindowElementList ( [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SWindow](API\Runtime\SlateCore\Widgets\SWindow) > ForWindow )